Samples, in particular tissue samples to be examined using a microscope, are routinely stained using staining devices, so that structures of the samples can be better seen in the microscopic image than in the case of unstained samples. For sample staining, a staining device includes two or more containers in which identical, similar or different process media are stored. The samples to be stained are immersed in the containers, where they remain for residence times which are dependent on the process step, the process medium, and on the sample to be stained. Once the predetermined residence time has elapsed, the samples are withdrawn from the container. Depending on the staining method and/or the sample, the samples are successively immersed in a plurality of containers filled with process media.
When the samples are rapidly withdrawn from a first container filled with a first process medium, small amounts of the first process medium remain adhered to the samples, in particular tissue samples, to slides carrying the tissue samples and/or to a sample basket for carrying the samples, and/or drip off from the samples once they are withdrawn from the process medium. When the samples are then rapidly moved over a second container which follows the first container and is filled with a second process medium, then the first process medium of the first container drips into the second process medium of the second container. When the samples are immersed in the second process medium in the second container, then all of the first process medium adhering to the samples gets into the second process medium. In this manner, the first process medium is entrained, causing the amount of the first process medium in the first container and the quality of the second process medium in the second container to be reduced. This has a negative effect on the quality of the staining process. In particular, the stained samples may have less color contrast and/or a lower color content. If, in contrast, the samples are slowly withdrawn from the first process medium and left suspended above the first container for a long time after withdrawal, then this reduces entrainment, but has a negative effect on the duration of the staining process in that it increases the same.
From the document DE 196 81 642 C2, a staining device for staining tissue samples on slides is known, which comprises a plurality of containers with liquids, said containers being arranged in a stepped manner relative to one another. Baskets in which the slides are accommodated are immersed in the containers for staining. Upon removal via a transport mechanism, the baskets are removed such that they brush against an edge of the respective container so as to wipe off liquid adhering to the basket.
From the document U.S. Pat. No. 5,573,727 A, a staining device is known which comprises a plurality of containers with liquids in which the racks with the samples to be stained are immersed. Here, several racks are simultaneously handled in the device, the transport of the racks taking place according to a fixed schedule.